1. Field of the Invention
This invention relates to a radiation image recording method, and more particularly to a method of recording a radiation image on a stimulable phosphor which emits light upon stimulated with stimulating rays.
2. Description of the Prior Art
In a method of recording a radiation image on a stimulable phosphor, a stimulable phosphor is first exposed to radiation carrying image information to store the energy of the radiation in the phosphor. Then, the phosphor is exposed to stimulating rays to be stimulated thereby and emit light carrying the image information. The emitted light carrying the image information is used for modulating a light beam to record an image on a photographic film or the like. Thus, the radiation image is recorded on a photographic recording material. As the radiation is used X-rays, .alpha.-rays, .beta.-rays, .gamma.-rays or ultraviolet rays, and as the stimulating rays is used visible light or infrared rays.
For example, in U.S. Pat. No. 3,859,527 is disclosed a method of recording on and reproducing from a stimulable phosphor a radiation image. In this method, a radiation image is once recorded on the stimulable phosphor and is read out therefrom by use of a heat ray or laser beam which stimulates the phosphor. The phosphor emits light upon stimulated and the emitted light is used to record the read out image on a final recording material.
In the above mentioned method of recording radiation images it is necessary to store a proper amount of energy in the stimulable phosphor at first. Further, it is necessary to record the radiation image finally on the recording material in proper density or contrast. It is very difficult however to know the proper amount of energy to be stored in the stimulable phosphor or to control properly the density of the finally obtained image on the recording material. This is because the detection of the energy stored in the stimulable phosphor requires destructive inspection in which the stored energy is partly emitted. This is further because the information which shows the various data of the radiation image first recorded to be used for controlling the final recording means to obtain proper density of the final image requires a great number of memories. In other words, in order to obtain the various data such as the maximum value, the minimum value, the average value of the stored energy of the all points of the image and the contrast of the image the information of the all points of the image must be once input into the memory and calculated after all the data have been memorized. Therefore, a memory device of great capacity is needed in order to obtain proper density of the final image. Furthermore, in this case there is needed a long time for the recording system to finally record the radiation image after analysis of the data and control of the density and/or contrast.